1. Field of the Invention
This invention relates to an apparatus for producing a stranded cable for an electric wire or cable.
2. Description of the Prior Art
Conventionally, such an apparatus as shown in FIGS. 3 and 4 is known as an apparatus for producing a stranded cable. Referring to FIGS. 3 and 4, the apparatus shown includes a driven wheel 14 having an annular recess or groove 15 formed on an outer periphery thereof. An annular stationary shoe member 17 is disposed on the outer periphery of the driven wheel 14 and has an inner circumferential face which serves as a guide face for rotation of the driven wheel 14. The stationary shoe member 17 has an annular inward projection or flange 19 formed on the inner circumferential face thereof, and the annular projection 19 extends into the annular groove 15 of the driven wheel 14 to define a passageway 21 for wire stock 20 fed thereto by way of a supply passageway 18.
The supply passageway 18 is formed in the stationary shoe member 17 for supplying wire stock 20 as a rough drawing wire therethrough into the passageway 21, and a guide roller 22 is disposed adjacent the supply passageway 18. An inner periphery 19a of the annular projection 19 of the stationary shoe member 17 gradually approaches an outer surface 15a of the annular groove 15 of the driven wheel 14 in the direction of rotation of the driven wheel 14 from the supply passageway 18 so that the sectional area of the passageway 21 defined by inner walls of the annular groove 15 and the annular projection 19 may gradually decrease in the counterclockwise direction in FIG. 4 from the position of the guide roller 22.
The driven wheel 14 has an axial center bore 23 formed therein, and a plurality of dies 26 are disposed in a concentrical relationship around the axial center bore 23 of the driven wheel 14 adjacent the passageway 21 which is defined by the inner walls of the annular groove 15 of the driven wheel 14 and the annular projection 19 of the stationary shoe member 17. In particular, threaded bores 25 are formed in parallel to the axial center bore 23 in a front end portion 24 of the driven wheel 14 and communicate with the passageway 21. A die holder 27 having an orifice 28 formed therein is threaded in each of the threaded bores 25, and a die 26 is supported at an end portion of each of the die holders 27 adjacent the passageway 21.
With the apparatus having such a construction as described above, rough drawing wire stock 20 is supplied into the passageway 21 through the supply path 18 of the stationary shoe member 17 past the guide roller 22 and is then advanced in the passageway 21 of the driven wheel 14 due to frictional force thereof with the latter as the driven wheel 14 rotates. During such advancement of the rough drawing wire stock 20, it is compressed by the driven wheel 14 and the stationary shoe member 17 as the sectional area of the passageway 21 gradually decreases. Then, when a predetermined compression stress is reached, the rough drawing wire stock 20 is successively extruded from the dies 26 adjacent the passageway 21 to form wires 33 having a desired diameter. Each of the wires 33 thus formed then passes two successive tension adjusting rollers 29 which are driven to rotate along with the driven wheel 14 while it is maintained under a predetermined constant tension by the tension adjusting rollers 29. In the meantime, a core wire 32 is supplied through the axial center bore 23 of the driven wheel 14. The wires 33 and the core wire 32 then pass through a twisting plate 30 and are then twisted with each other by a twisting die 31 to form a concentric lay cable 34 of a single layer. The cable 34 is successively wound up on a take-up drum not shown by way of a capstan.
Upon such conventional extrusion molding which employs a frictional force, since the wire stock between the driven wheel and the stationary shoe is acted upon by frictional forces in the opposite directions and besides the inner face of the annular projection of the stationary shoe has an irregular configuration, it is a drawback that a high production cost is required. Further, since the annular projection of the stationary shoe is fitted over the entire periphery thereof in the annular groove of the driven wheel, it is necessary, upon assembly of the apparatus, to divide either the stationary shoe or the driven wheel. Accordingly, also it is a drawback that much time is required for maintenance.